Vegetative Plant Description: The trailing pubescent stems (terete or angled) grow up to 2.5m. The primocanes of this species are intensely bristly with up to 200 bristles and glands per centimeter on the stem. Even the petioles of primocane leaves have hundreds of bristles, although the floricanes are less bristly. Stems often root at the tips. Leaves are pinnately compound and alternate, with 3-5 leaflets. The evergreen, coriaceous leaflets are pubescent below, serrate, obovate, acuminate, and range from 2 to 6cm long and 1 to 4cm wide (1, 2, 21).

Flower Description: The inflorescence is a cyme of small white-petaled flowers. Each flower bears 3-7 sepals (3-5mm) that are oblanceolate and hairy, 5 petals (5-9mm long, 2-5mm wide), and stamens and carpels that are numerous. Styles are terminal on each carpel. Dewberries have two ovules per pistil (usually between 20-40 pistils per flower), which will mature into the seeds (2,6,21,23).

Flowering Time: Flowers from June through early September in the Central and Northeastern United States and adjacent Canada (2).

Pollinator: insects, including honeybees (9,23).

Fruit Type and Description:R. hispidus matures the black fruits from mid August to October. The fruit type is an aggregate of drupelets (75-85) that turn from green to red to black as the fruit matures (2,8, 23). Birds disperse the fruits, as well as the casual hiker.

Seed Description: The small seeds are bird dispersed, high in sugar, low in lipids, and usually are not retained on the plant for long. The seed requires cold stratification for germination (16, 17).

Dispersal Syndrome:R. hispidus reproduces sexually if visited by insect pollinators, and birds often disperse the seeds, but it also engages in vegetative reproduction through clonal expansion. A study by Abrahamson (1975) indicates that sexual reproduction is preferred when the plant is growing in dense woods, while vegetative reproduction is preferred in open areas (8,9,10,16).

Distinguished by: Rubus hispidus var. hispidus can be differentiated from R. hispidus var. obovalis by the thickness of the stems, the number of bristles, and the size of terminal leaflets. R. hispidus var. hispidus stems are 2-5mm thick, with 30-200 bristles per cm and a terminal leaflet 2.5-7 cm. long and 2-5.5 cm. wide. R. hispidus var. obovalis stems are thinner, measuring only 1-2mm thick, with 1-20 bristles per cm. and a smaller terminal leaflet measuring 1.5-4.5 cm. long and 1-3.5 cm. wide. Compared to R. flagellaris, R. hispidus bristles are thinner and longer, not often with broad bases like the shorter bristles on R. flagellaris. The inflorescence in R. flagellaris, and especially R. setosus, are very likely to be glandular while R. hispidus rarely show this trait. The flatter-topped inflorescence in R. setosus is another distinctive trait, and even though the bristles are very similar to R. hispidus, the erect stems do not root at the tips as in R. hispidus, whose stems trail and root. R. trivialis has glandular bristles and single flowers while R. hispidus bristles are eglandular and flowers are aggregated. R. allegheniensis is also distinguished by the erect primocane with broad-based spines. R. caesius has spines, but not bristles. Rosa eglanteria’s leaves have odor, the thorns have a large base and slightly more leaflets than R. hispidus, which is not fragrant and has fine bristles. Rosa setigera bears red receptacle-derived fruits (hips), broad-based curved thorns, and pink flowers, while R. hispidus’ fruits are black drupelets and its flowers are white (2,3,5,20,21).

Ethnobotanical Uses: Native Americans used the roots to treat cough, fever, and diarrhea. The fruits were used to treat dysentery (14, 15).

Phylogenetic Information: The genus Rubus is classified as member of the subfamily Rosoideae in the Rosaceae, which is in the order Rosales, a Eudicot clade of the angiosperms. Members of the Rosaceae family can be found worldwide, and the genus Rubus is found in both north and south temperate climatic zones (18, 22).

Interesting Quotation or Other Interesting Factoid not inserted above: Hybrids derived from a cross between R. hispidus and other Rubus species, such as R. setosus, are found in Michigan: R. distinctus, R. kalamazoensis, R. plus, and R. signatus (20).

Literature and websites used:

Parkhurst, H.E. 1903. Trees, shrubs and vines of the northeastern United States. New York, New York, USA: C. Scribner’s Sons.

Image Credits (all used with permission):1) Habit image of Rubus hispidus courtesy of Cofrin Center for Biodiversity, Gary Fewles photographer, http://www.uwgb.edu/biodiversity/herbarium/shrubs/rubhis_aspect01.jpg2, 3) Image of leaves and flower courtesy of Will Cook from the website “Trees, Shrubs, and Woody Vines of North Carolina” at http://www.duke.edu/~cwcook/trees/ruhi.html
4) Fruit image courtesy of K.J. Sytsma, Wisconsin State Herbarium, photo taken in Kalamazoo Michigan during his master’s thesis at Western Michigan University http://www.botany.wisc.edu/wisflora/
5) Image of seeds courtesy of Julia Scher, USDA APHIS PPQ, Bugwood.org http://www.forestryimages.org/browse/detail.cfm?imgnum=53767496) Species distribution map, derived from the Michigan Flora Online.

Primary Authors: Cristine Santanna with editing by John Bradtke and Robyn J. Burnham